Room lighting calculator
Work out how much light a room needs and how many bulbs to buy. Pick the room type — it sets the recommended illuminance in lux — enter the dimensions and your bulb's lumen output, and it returns the total lumens required and the number of fixtures, adjusted for tall ceilings.
Related tools
All Interior & storage tools →Need Floor area (m²), Total lumens needed, Bulbs / fixtures needed? The Room lighting calculator derives it from Room type, Measure in, Room length, Room width, Ceiling height (0 = standard), Lumens per bulb in one step. For instance, with Room type = Living room (200 lux), Measure in = Feet, Room length = 15, Room width = 12, Ceiling height (0 = standard) = 0 and Lumens per bulb = 800 it returns Floor area (m²) = 16.723, Total lumens needed = 3,345 and Bulbs / fixtures needed = 5.
How to use it
- Enter your values: Room type, Measure in, Room length, Room width, Ceiling height (0 = standard), Lumens per bulb.
- Read the result instantly: Floor area (m²), Total lumens needed, Bulbs / fixtures needed.
Frequently asked questions
What does the Room lighting calculator actually compute?
It takes Room type, Measure in, Room length, Room width, Ceiling height (0 = standard) and Lumens per bulb and derives Floor area (m²), Total lumens needed and Bulbs / fixtures needed from them. The calculation is live as you type, so the result updates on every change.
What information do I need to provide?
6 values: Room type, Measure in, Room length, Room width, Ceiling height (0 = standard) and Lumens per bulb. Nothing else is required — no account, no file upload.
Can you show a worked example?
With Room type = Living room (200 lux), Measure in = Feet, Room length = 15, Room width = 12, Ceiling height (0 = standard) = 0 and Lumens per bulb = 800, the calculator returns Floor area (m²) = 16.723, Total lumens needed = 3,345 and Bulbs / fixtures needed = 5. Those figures come from running this exact tool, so you can reproduce them by entering the same values.
What happens if I enter larger values?
It moves a lot. Using Room type = Bedroom (150 lux), Measure in = Meters, Room length = 30, Room width = 24, Ceiling height (0 = standard) = 5 and Lumens per bulb = 1,600 instead, Floor area (m²) goes from 16.723 to 720 — which is why it is worth testing a few scenarios rather than trusting a single figure.
Which “Room type” option should I choose?
You can pick between « Living room (200 lux) », « Bedroom (150 lux) », « Kitchen — general (300 lux) », « Kitchen counter / task (500 lux) », « Bathroom (300 lux) » and « Dining room (200 lux) ». Each one changes what the calculator works out, so switch and compare — the default is « Living room (200 lux) ».
What does it give for smaller values?
Scaled down to Room type = Living room (200 lux), Measure in = Feet, Room length = 8, Room width = 6, Ceiling height (0 = standard) = 1 and Lumens per bulb = 400, Floor area (m²) comes out at 4.459. The relationship is worth checking at both ends before you rely on a single result.
When would I actually use this?
Working out whether it fits: how many boxes a move needs, what size storage unit holds them, and whether a piece of furniture clears the space.
What is the most common mistake?
Sizing storage by floor area alone. Units are stacked to the ceiling in practice, so height changes the answer as much as footprint does — and access space has to be left in front.
What is the difference between the Room lighting calculator and the Lux to lumens calculator?
This one returns Bulbs / fixtures needed; the Lux to lumens calculator returns Bulbs needed. That is the whole difference — open the one whose figure you need.
Where do the figures come from, and how current are they?
The geometry is exact for the dimensions you enter. Standard box and unit sizes differ between the US and Europe, and the tool shows both rather than converting one into the other.